JPH1025258A - Alkylation of cyclopentadiene-based compound - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for introducing an alkyl group into a cyclopentadiene-based compound, excellent in operating efficiency and safety, and in a high yield by reacting a specific amount of an alkyllithium with the cyclopentadiene-based compound. SOLUTION: This method for alkylating a cyclopentadiene-based compound is to react the cyclopentadiene-based compound with an equivalent molar or a little less than the equivalent molar amount of an alkyllithium, add a dipolar aprotic solvent (e.g.; 1,3-dimethyl-2-imidazolidinone) into the reaction solution, and then react the obtained compound with an alkyl compound of the formula: RX (R is a 1-15C hydrocarbon; X is tosyl, methyl or a halogen) at -78 to 50 deg.C for 1hr to one night under agitation. The obtained alkylcyclopentadiene- based compound is a synthetic precursor for an alkylcyclopentadienyl complex useful as a hydrogenation catalyst, a reagent for an organic synthesis, an olefin polymerization catalyst, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for synthesizing an alkylcyclopentadiene compound which is a precursor for the synthesis of an alkylcyclopentadienyl complex useful as a hydrogenation catalyst, a reactant for organic synthesis or a catalyst for olefin polymerization. Things.

[0002]

BACKGROUND ART Alkylcyclopentadiene compounds are
It is a synthesis precursor of an alkylcyclopentadienyl complex useful as a hydrogenation catalyst, a reactant for organic synthesis, or a catalyst for olefin polymerization.

Conventionally, the following three methods are mainly known as methods for synthesizing alkylcyclopentadiene compounds. The first method is a method in which cyclopentadiene is reacted with a lower aliphatic alcohol in a gas phase using an alkali metal compound or an alkaline earth metal compound as a catalyst (see EP 0158189: Method A). In the second method, an alkali metal oxide and an alkali metal hydroxide, or an alkaline earth metal oxide and an alkaline earth metal hydroxide are mixed with cyclopentadiene using a glycol diether solvent such as diethylene glycol ethyl ether as a reaction solvent. This is a method of reacting an alkyl halide in the presence of a substance (see US Pat. No. 5,336,795: Method B). A third method is to convert cyclopentadiene into an alkali metal salt and then react the salt with an alkyl halide (JP-A-6-15756).
No. 9: Method C). Of these three methods,
Method A requires a special reaction apparatus for performing a gas phase reaction, and method B requires the use of an expensive solvent as a reaction solvent. On the other hand, the method C is a method using an inexpensive raw material in which, for example, a cyclopentadienyl sodium is synthesized and then an alkyl halide is reacted, but has the following problems in consideration of safety and operability.

That is, cyclopentadienyl sodium is obtained by reacting cyclopentadiene with metallic sodium or sodium hydride, but it is necessary to use finely dispersed metallic sodium. Alternatively, sodium hydride aggregates during the reaction with the cyclopentadiene compound to form a lump of metallic sodium, which involves danger during post-treatment.

[0005] Cyclopentadienyllithium, which is an alkali metal salt, can be easily synthesized by reacting a commercially available alkyllithium solution with cyclopentadiene. There is a problem that the reactivity to alkyl is low, and the yield of the generated alkylcyclopentadiene is low (see Maruzen Co., Ltd., 1991, Experimental Chemistry Lecture, Vol. 25, p. 11). Although its reactivity with alkyl is high, there is an operational problem that its synthesis requires the use of potassium metal or potassium hydride, which is highly ignitable and requires careful handling.

[0006]

DISCLOSURE OF THE INVENTION The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, introduced an alkyl group into a cyclopentadiene-based compound with excellent operability and safety and in a high yield. I found a way. The present invention has been made based on such findings.

According to the present invention, a cyclopentadiene compound is reacted with an equimolar amount or slightly smaller amount of alkyllithium with respect to the cyclopentadiene compound, and a dipolar aprotic solvent is added to the reaction solution. After that, an alkyl compound represented by the formula RX (wherein R represents a hydrocarbon group having 1 to 15 carbon atoms and X is a tosyl group, a mesyl group or a halogen atom) is reacted. An object of the present invention is to provide a method for alkylating a cyclopentadiene-based compound.

Hereinafter, the present invention will be described in detail.

The alkylation method according to the present invention is effective for various cyclopentadiene compounds such as cyclopentadiene compounds, indene compounds, and fluorene compounds. Examples thereof include alkylcyclopentadiene, dialkylcyclopentadiene, trialkylcyclopentadiene, tetraalkylcyclopentadiene, and indene.

The alkyl lithium is a reagent used for converting a cyclopentadiene compound to the corresponding cyclopentadienyl lithium, and examples thereof include n-butyl lithium, sec-butyl lithium, and tert-butyl lithium. Many of the respective lithium compounds are commercially available as solutions such as hexane. Preferably, a hexane solution of n-butyllithium is used. R in the formula RX is a hydrocarbon group having 1 to 15 carbon atoms. X is a leaving group, and examples thereof include a tosyl group, a mesyl group and a halogen group. Preferably, it is a halogen group, such as a chlorine atom, a bromine atom or an iodine atom. Examples of the dipolar aprotic solvent include 1,3-dimethyl-2-imidazolidinone and hexamethylphosphoric triamide.

The alkylation method of the present invention will be briefly described below.

The reaction between the cyclopentadiene compound and the alkyl lithium is performed by converting the cyclopentadiene compound into hexane,
It is dissolved in a solvent such as toluene, diethyl ether, tetrahydrofuran or 1,2-dimethoxyethane, and is dissolved at a reaction temperature of −78 ° C. to 20 ° C. in an amount of about 0.8 to 1.0 molar equivalent relative to the cyclopentadiene compound. The alkyl lithium solution was added dropwise, and then the reaction temperature was -78 ° C.
To 50 ° C. by stirring for 30 minutes to 2 days. If the alkyl lithium is used in excess, a cyclopentadiene compound in which R is substituted by two or more is produced as a by-product in the reaction with RX in the subsequent step, so that the alkyl lithium is the same molar amount or slightly smaller than the cyclopentadiene compound. It is appropriate to use molar amounts, preferably about 0.85 to 0.95 molar equivalents.

The resulting reaction solution is maintained at a reaction temperature of -78 ° C. to 20 ° C., and 1.0 to 3.0 molar equivalents of a dipolar aprotic solvent are added thereto and stirred for 10 minutes to 6 hours.
To this, at a reaction temperature of −78 ° C. to 50 ° C., preferably, the reaction temperature is controlled so as not to exceed 20 ° C., and about 0.8 to 1.0 molar equivalent of the RX compound is added to the cyclopentadiene compound. I do. Then, the reaction temperature was -78 ° C.
The reaction is carried out at from to 50 ° C. under stirring for 1 hour to overnight. After completion of the reaction, the reaction mixture is added to a saturated saline solution and the like, and the separated organic solvent layer is washed and concentrated to obtain the desired alkylcyclopentadiene compound. The alkylcyclopentadiene compound thus obtained can be purified by distillation, but can be used without purification for synthesizing a cyclopentadienyl complex as it is.

Next, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

[0015]

【Example】

Example 1 In a 1-liter four-necked flask, 40 ml (485 mmol) of cyclopentadiene and 260 ml of tetrahydrofuran were charged in an argon atmosphere. After ice cooling, add n-
260 mL (437 mmol) of a BuLi hexane solution was added dropwise over 1 hour. Then, the mixture was returned to room temperature and stirred for 3 hours. After cooling the reaction mixture with ice, 57.3 ml (524 mmol) of 1,3-dimethyl-2-imidazolidinone was added, and the mixture was stirred at the same temperature for 30 minutes. Then n-butyl bromide 59.8
g (437 mmol) was added dropwise over 15 minutes. The liquid temperature gradually increased, but was controlled so as to be 20 ° C. or less. After the dropwise addition, the temperature was returned to room temperature, and the mixture was stirred overnight.

After the reaction solution was cooled with ice, it was poured into 45 ml of a saturated aqueous solution of ammonium chloride. After layer separation, the organic layer was washed with saturated saline 5
Washed 5 times with 0 ml. The organic layer was dried over sodium sulfate and concentrated to obtain 67.3 g of a yellow oily substance.

As a result of gas chromatography analysis, the obtained oily substance was found to contain 29% of the solvent and 64% of the main component, and hardly any by-products were found. The main component on gas chromatography is that the molecular ion peak is M
⁺ = 122, and it was confirmed to be n-butylcyclopentadiene. Further, a small amount was taken in an eggplant-shaped flask, and the solvent was completely distilled off. Then, ¹ H-NMR was measured. As a result, it was confirmed that the product was the target product (mixture of tautomers). The yield was calculated to be 81%, based on the content of gas chromatography.

¹ H-NMR (CDCl ₃ / TMS) δ 0.88-0.98 (m, M
e, 3H), 1.26-1.43 (m, CH ₂ CH ₂ , 4H), 2.33 (br, CH ₂ , 2
H), 2.84-2.94 (m, CH ₂ (in Cp ring), 2H), 5.97-6.42 (m, Cp
Ring, 3H) Example 2 Under an argon atmosphere, 200 ml (2.40 mol) of cyclopentadiene and 1.4 liter of tetrahydrofuran were charged into a 5-liter four-necked flask. After ice cooling, add n
-BuLi hexane solution 1.5 liter (2.40 mol) was added dropwise over 1 hour. Then, the mixture was returned to room temperature and stirred for 3 hours. After cooling the reaction solution on ice, 415 ml (3.38 mol) of hexamethylphosphoric triamide was added, and the mixture was stirred at the same temperature for 30 minutes. Then, n-butyl bromide 260 ml
(2.40 mol) was added dropwise over 1 hour. The liquid temperature gradually increased, but was controlled so as to be 20 ° C. or less. After the dropwise addition, the temperature was returned to room temperature, and the mixture was stirred overnight.

After the reaction solution was cooled with ice, it was poured into 300 ml of a saturated saline solution. After separation, the organic layer was washed five times with 300 ml of saturated saline. The organic layer was dried over sodium sulfate and concentrated to obtain 280 g of a yellow oily substance. This was distilled under reduced pressure to obtain 236 g of n-butylcyclopentadiene.
Gas chromatography analysis revealed that the solvent contained 15% and the target substance 85%. The yield was calculated to be 68% in terms of gas chromatography content. Example 3 Under an argon atmosphere, 32.4 g (374 mmol) of methylcyclopentadiene and 216 ml of tetrahydrofuran were charged into a 500 ml four-necked flask. After cooling with ice, 216 ml (337 mmol) of a n-BuLi hexane solution was added dropwise over 1 hour. Then return to room temperature 3
Stirred for hours. After cooling the reaction solution on ice, 1,3-dimethyl-2
-44.2 ml (404 mmol) of imidazolidinone were added and stirred at the same temperature for 30 minutes. Then, 36.2 ml (337 mmol) of n-butyl bromide were added dropwise over 15 minutes. The liquid temperature gradually increased, but was controlled so as to be 20 ° C. or less. After the dropwise addition, the temperature was returned to room temperature, and the mixture was stirred overnight.

After treating the reaction mixture in the same manner as in Example 1, distillation under reduced pressure (boiling point: 40 ° C. to 45 ° C./degree of reduced pressure: 15 mm
Hg) to obtain 37.4 g of a mixture of 1-butyl-2-methylcyclopentadiene and 1-butyl-3-methylcyclopentadiene. Gas chromatography analysis revealed that the solvent contained 30% of the target compound (mixture of position and tautomer).
Was contained 70%. The mixture of regio- and tautomers was confirmed to have a molecular ion peak at M ⁺ = 146 from gas chromatography / mass spectrum, and was confirmed to be cyclopentadiene substituted with a butyl group and a methyl group. The yield was calculated to be 70% in terms of gas chromatography content. Example 4 A 1-liter four-necked flask was charged with 52 ml (631 mmol) of cyclopentadiene and 338 ml of tetrahydrofuran in an argon atmosphere. After ice cooling, add n-
338 ml (564 mmol) of a BuLi hexane solution was added dropwise over 1 hour. Then, the mixture was returned to room temperature and stirred for 3 hours. After cooling the reaction solution with ice, 68.1 ml (681 mmol) of 1,3-dimethyl-2-imidazolidinone was added, and the mixture was stirred at the same temperature for 30 minutes. Then n-propyl bromide 69.
3 g (564 mmol) were added dropwise over 15 minutes. The liquid temperature gradually increased, but was controlled so as to be 20 ° C. or less.
After the dropwise addition, the temperature was returned to room temperature, and the mixture was stirred overnight.

After the reaction solution was cooled on ice, it was poured into 60 ml of a saturated aqueous solution of ammonium chloride. After layer separation, the organic layer was washed with saturated saline 5
Washed 5 times with 0 ml. The organic layer was dried over sodium sulfate and concentrated to give a yellow oil. This was distilled under reduced pressure (boiling point: 38 ° C. to 42 ° C./degree of reduced pressure: 25 to 30 mmHg) to obtain 32.2 g of a pale yellow oily substance. Gas chromatography analysis revealed that the solvent contained 5.4% and the target compound 94.6%. From the gas chromatography mass spectrum, the molecular ion peak of the main component on gas chromatography was confirmed at M ⁺ = 108, and it was confirmed that the main component was n-propylcyclopentadiene. The yield was calculated to be 50% in terms of gas chromatography content.

[0022]

[Comparative example]

Comparative Example Under an argon atmosphere, 95 ml (1.16 mol) of cyclopentadiene and 1.0 liter of tetrahydrofuran were charged into a three-liter four-necked flask. After ice cooling, add n-
725 ml (1.16 mol) of a BuLi hexane solution was added dropwise over 1 hour. Then, 125 ml of n-butyl bromide
(1.16 mol) was added dropwise over 1 hour. Liquid temperature is 20
It controlled so that it might become below ° C. After the dropwise addition, the temperature was returned to room temperature, and the mixture was stirred overnight.

After the reaction solution was cooled with ice, it was poured into 300 ml of a saturated aqueous solution of ammonium chloride. After separation, the organic layer was washed five times with 300 ml of saturated saline. The organic layer was dried over sodium sulfate and then concentrated to obtain 150 g of a brown oily substance.
As a result of analyzing the obtained oily substance by gas chromatography, 40% of n-butylcyclopentadiene was produced, but 27% of n-butyl bromide as a raw material remained.
This was distilled under reduced pressure to obtain n-butylcyclopentadiene 5
0.8 g was obtained. Gas chromatography analysis indicated that the solvent contained 10% and the target substance 90%. The yield was calculated to be 32% when converted by gas chromatography content.

[0024]

【Example of use】

Use Example The n-butylcyclopentadiene synthesized in Example 1 was used in this reaction without purification.

Under an argon atmosphere, 67.3 g of n-butylcyclopentadiene (64
% Content 353 mmol) and 250 ml of toluene. After cooling with ice, 252 ml (423 mmol) of a hexane solution of n-butyllithium was added dropwise over 1 hour. Thereafter, the mixture was stirred at room temperature for 3 hours. Then, after cooling the reaction solution, 53.4 g (229 mmol) of zirconium chloride was added, and the mixture was heated under reflux for 3 hours. After cooling, 200 ml of 4N hydrochloric acid was added, and the mixture was stirred at room temperature for 30 minutes. After separation,
The organic layer was washed four times with 200 ml of a saturated saline solution and dried over magnesium sulfate. The organic layer was concentrated to give crude crystals 79.9
g was obtained. This was purified by recrystallization to give 50.4 g of white crystals.
I got The obtained white crystals were analyzed by ¹ H-NMR to obtain dichlorobis (n-butylcyclopentadienyl).
It was confirmed to be zirconium. Yield 71% ¹ H-NMR (CDCl ₃ / TMS) δ 0.81-0.98 (t, Me, 6H), 1.15-
1.70 (m, CH ₂ CH ₂ , 8H), 2.64 (t, CH ₂ , 4H), 6.20-6.33 (m,
(Cp ring, 8H)

Continued on the front page (72) Inventor Masahiro Yoshida 1-7-1 Inari, Soka City, Saitama Prefecture Kanto Chemical Co., Ltd. Central Research Laboratory

Claims (2)

[Claims] 1. A cyclopentadiene-based compound is reacted with an equimolar amount or a slightly smaller molar amount of alkyllithium with respect to the cyclopentadiene-based compound, and a dipolar aprotic solvent is added to the reaction solution. , Formula RX
(Wherein, R represents a hydrocarbon group having 1 to 15 carbon atoms, and X is a tosyl group, a mesyl group or a halogen atom). A cyclopentadiene characterized by reacting A method for alkylating a series compound. 2. The method according to claim 1, wherein the dipolar aprotic solvent is 1,3-dimethyl-2-imidazolidinone, and X in the formula RX is a halogen atom.